Heat exchanger for secondary refrigerating systems



April 11, 19 50 F. A. SCHUMACHER HEAT EXCHANGER FOR SECONDARY REFRIGERATING SYSTEM Filed Oct. 22, 1947 lnverwtorz Frahk A.Schumacherj by M 12 His Attorney.

Patented Apr. 11, 1950 HEAT EXCHANGER FOR SECONDARY REFRIGERATING SYSTEMS Frank A. Schumacher, Erie, Pa., assignor to General Electric Company, a corporation of New York Application October 22, 1947, Serial No. 781,325

4 Claims. (Cl. 62125) My invention relates to refrigerating systems and more particularly to refrigerating systems of the closed secondary type.

Some refrigerators are provided with two compartments refrigerated by separate evaporators maintained at different temperatures, one compartment being used for frozen food and the other compartment being used for fresh food. It is desirable in some cases to maintain the surface temperature of the cooling unit for the fresh food compartment slightly above 32 F. so as to obtain a high humidity atmosphere in the compartment and to prevent the formation of frost. The cooling of the fresh food compartment may be provided by a secondary refrigerating system employing a volatile liquid as its refrigerant. The secondary system may comprise a closed conduit or loop of tubing partially filled with the liquid refrigerant and arranged to provide a vapor condensing portion and a liquid evaporating portion. The condensing portion of the secondary system is connected to be cooled by the primary evaporator and arranged so that the condensed refrigerant flows back to the evaporating portion of the secondary system. Since the primary evaporator, which supplies refrigeration for the frozen food compartment, is normally operated at about F., the condensed refrigerant in the secondary system may be cooled substantially below 32 F. before flowing away from the condensing portion. Delivery of liquid refrigerant to the evaporating portion at temperatures well below' 32 F. is objectionable and may cause localized frosting. It is desirable to minimize the supplying of liquid refrigerant at such low temperatures to the evaporating portion of the secondary system in order to maintain the temperature of the evaporating portion in the neighborhood of 32 F,

Accordingly, it is an object of my invention to provide an improved heat exchange arrangement for a secondary refrigerating system.

Further objects and advantages of my invention will become apparent as the following description proceeds and the features of novelty which characterize my invention will be pointed of a metallic shell I which forms the liner of the frozen food compartment. This compartment is refrigerated by a primary evaporator 2 secured in heat exchange relation with the exterior of the shell Liquid refrigerant is supplied to the primary evaporator from any suitable refrigerout with particularity in the claims annexed to and forming part of this specification.

For a better understanding of my invention reference may be had to the accompanying drawing in which Fig. 1 is a schematic perspective view showing an embodiment of my invention applied to a closed secondary refrigerating system; and Fig. 2 is a view taken along the lne 2-2 in Fig. 1 of a valve illustrated in Fig. 1.

Referring now to Fig. 1 there is shown a portion secured to the metal liner ating apparatus (not shown) through a restricted conduit 3 acting as an expansion device, and vaporized refrigerant is withdrawn from the other end of the primary evaporator through a suction line (not shown).

In order to refrigerate the fresh food compartment a closed secondary refrigerating system employing a refrigerant of the volatile liquid type is provided. This secondary system includes a condensing portion [and an evaporating portion 5, the portion 5 being partially filled with a vaporizable liquid refrigerant. A valve 6 is provided between the condensing portion and the evaporating portion for controlling the-flow of refrigerant in the secondary system. To effect withdrawal of heat from the secondary system the condensing portion 4 is arranged in heat exchange relationship with a portion 1 of the primary evaporator 2.

The evaporating portion 5 is shown only sche-.

matically in this figure but it may be located in any suitable relation with the fresh food compartment for refrigeration of that compartment. For example, the evaporating portion may be of the fresh food compartment.

The evaporating portion 5 is connected in open communication with a chamber 8 within the valve v5 by conduits 9 and I0. Conduit II is provided housing l3 composed of two complementary cupshaped parts It and l5.- The two parts l4 and 15 are secured to a central support member It in sealing relationship to form a unitary housin'g structure. The chamber 8, previously referred to, is located within the portion l5 of the housing, and the conduits 9 and ID are connected in open communication with this chamber. The conduit H, shown in Fig. 1, is also in open communication with this chamber. Within the housing l3 there is located a valve element II for controlling the flow of liquid refrigerant from the condensing portion 4 through the conduit I2 and thence through the conduit 9 to the evaporating portion 8. The valve element i1 is arranged for reciprocation within a hollow guide cylinder II, and two thin lands I I are provided for facilitating movement along the interior of the cylinder. A spring 20 is provided for biasing the valve element toward its open position, one end of the spring engaging the closed end of the cylinder l8 and the other end of the spring engaging one of the lands I8. Movement of the valve element is controlled by a bellows it. .One side of the bellows is subjected to the pressure of the refrigerant in the evaporating portion and the other side of the bellows is subjected to the pressure of a charge of an inert gas, such as nitrogen, in a closed chamber 22 formed between the exterior of the bellows 2i and the portion l4 of the housing. In order to prevent binding of in to the chamber 8 in valve 6. The vaporized refrigerant passes from the chamber 8 through the conduit II, which is in open communication with the chamber 8, and thence into the condensing portion 4. The vaporized refrigerant is condensed in the'condensing portion 4 as the .result of heat being'extracted by the primary evaporator 2 and the liquid refrigerant then flows downwardly into the conduit l2. If the valve element" is in its open position, the liquid refrigerant flows into the chamber 8 and thence from the chamber 8 through the conduit 9 back into the evaporator portion 5. As explained above, one side of the bellows M is subjected to the pressure of the refrigerant in the evaporating portion, since the'evaporating portion is in open communication with the chamber 8, and thus with the interior 'of the bellows 2|, through the conduit [0. As further explained above, the opposite side of the bellows is subjected to the pressure of a charge of inert gas in the closed chamber 22. The valve element i1 is biased toward its open position by the spring 20. When the pressure of the refrigerant in the evaporating portion 5, plus the biasing force exerted by the spring 23, exceeds the opposing pressure exerted by the inert gas in the chamber 22, the valve element I1 is moved to an open position and 4 irigerant within the condensing portion 4 will also tend to reach alow temperature of the order of 0 F. This is particularly true during periods when the refrigeration requirements of the evaporating portion 5 are low since, during such times, the valve 8 is closed and condensed refrigerant is held in the lower part of the condensing portion 4. It is undesirable to allow refrigerant of this low temperature to pass to the evaporating portion 5 since it would cause an undesirably low temperature at the bottom of the evaporating portion 5 and result in the formation of frost on the outside of the evaporating portion. In order to raise the temperature of this liquid refrigerant and to insure that liquid refrigerant is thereby raised so that it may be transmitted to the evaporating portion 5 without causing frosting. At the same time the heat withdrawn from the vaporized refrigerant causes a portion of the vaporized refrigerant to condense and this condensed refrigerant flows back into the chamber 8 and thence into the evaporating portion 5. In order to facilitate the flow of condensed refrigerant from the conduit H to the chamber 8 the conduit II is sloped toward the chamber 8 as indicated in the drawing. Similarly, to facilitate flow of liquid refrigerant from the condensing portion 4 through the valve 5 to the evaporating. portion 5 the vconduit I2 is sloped toward the valve 6.

Heat transfer between the vaporized and the liquid refrigerant is assisted by arranging the conduit ll below the conduit 12. This arrangement insures that any refrigerant condensing in.

- the conduit ll flows along the bottom of this flow of liquid refrigerant from the conduit l2 to to control the supplying of liquid refrigerant to the evaporating portion 5 in accordance with the temperature of this evaporating portion, and

' embodiment of my invention I do not desire my invention to be limited to the particular construction shown and I intend by the appended claims to cover all modifications in the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A closed secondary refrigerating system including a condensing portion and an evaporating portion and containing a refrigerant of the volahence in accordance with its refrigeration retile liquid type, means including a conduit for conducting vaporized refrigerant from said evaporating portion to said condensing portion, means including a second conduit for conducting liquid refrigerant from said condensing portion to said evaporating portion, means including alow temperature evaporator for extracting heat from said condensing portion, and a valve connected to said second conduit between said condensing portion and said evaporating portion for controlling the flow of liquid refrigerant, said valve being adapted in its closed position to hold liquid refrigerant in said second conduit and in said condensing portion, said conduits being arranged in heat exchange relationship with each other for raising the temperature of the liquid refrigerant substantially to the temperature of said evaporating portion before delivery to said evaporating portion.

2. A closed secondary refrigerating system including a condensing portion and an evaporating portion and containing a refrigerant of the volatile liquid type, means including a first conduit for conducting vaporized refrigerant from said evaporating portion to said condensing portion, means including a second conduit for conducting liquid refrigerant from said condensing portion to said evaporating portion, and means for maintaining said conduits in heat exchange relationship with each other to raise the temperature of the liquid refrigerant in said second conduit, said first conduit being sloped to direct refrigerant condensed therein back toward said evaporating portion.

3. A closed secondary refrigerating system including a condensing portion and an evaporating portion and containing a refrigerant of the volatile liquid type, means including a first conduit for conveying vaporized refrigerant from said evaporating portion to said condensing portion, and means including a second conduit for conveying liquid refrigerant from said condensing portion to said evaporating portion, said conduits being arranged in heat exchange relationship with each other to raise the temperature of 35 the liquid-refrigerant in said second conduit before delivery to said evaporating portion, said first conduit being arranged beneath said second conduit whereby any liquid resulting from con-..

densation of vaporized refrigerant in said first conduit flows along the side of said first conduit remote from said second conduit so that the heat exchange between said conduits is not affected.

4. A closed secondary refrigerating system including a condensing portion and an evaporating portion and containing a refrigerant of the volatile liquid type, means including a first conduit for conveying vaporized refrigerant from said evaporating portion to said condensing portion, and means including a second conduit for'conveying liquid refrigerant from said condensing portion to said evaporating portion, said conduits being arranged in heat exchange relationship with each other to raise the temperature of the liquid refrigerant in said second conduit, said second conduit being sloped toward said evaporating portion to cause the liquid refrigerant to flow toward said evaporating portion, said first conduit also being sloped toward said evaporating portion to cause vaporized refrigerant condensing therein to return to said evaporating portion.

FRANK A. SCHUMACHER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,028,565 Ruppricht Jan. 21, 1936 2,111,618 Erbach Mar. 22, 1938 2,359,595 Urban Oct. 3, 1944 

